Meteorology -Weather acloutier 2011 power point


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Continuing our unit on METEOROLOGY - Weather
Hurricanes & Storms
Coriolis Effect
Convection Cells

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Meteorology -Weather acloutier 2011 power point

  1. 1. WEATHER acloutier 2011 copyright Sun, heat, water, wind
  2. 2. We talk about the weather every day <ul><li>Observation and hypothesis > what will the weather be for the weekend? </li></ul>Meteorology is the study of the atmosphere Weather is the current state of the atmosphere Climate is the average weather over a long period of time
  3. 3. Air mass and movement of the planet <ul><li>Coriolis effect deflects air masses to the right in the northern hemisphere and to the left in the southern hemisphere </li></ul><ul><li>Coriolis effect combines with the heat imbalance found on Earth to form the trade winds, prevailing westerlies, and polar easterlies </li></ul>
  4. 4. Coriolis effect
  5. 5. Rotation and Convection Currents <ul><li>The Earth has gases in the atmosphere and water on the surface </li></ul><ul><li>The dense cold air of the poles sinks towards the surface , heading for the warm tropical air </li></ul><ul><li>The warm tropical air at the equator is forced to rise </li></ul>
  6. 6. Warm air rises, cold air sinks
  7. 7. Hadley Cells are convection cells
  8. 8. Polar cells, Hadley cells and Ferrel cells depend on each other to mix the temperatures on Earth
  9. 9. Three major wind systems in each hemisphere on Earth <ul><li>Doldrums happen at the equator 0* not much happens with wind here, the air hovers and is very hot </li></ul><ul><li>Trade Winds occur at the 30* north and south latitudes </li></ul><ul><li>Here cooler air sinks and heats up as it moves to the equator in a westerly direction </li></ul><ul><li>When it hits the equator it rises again and moves back to the 30*, and repeats the process </li></ul>
  10. 10. Prevailing westerlies <ul><li>Prevailing westerlies flow between 30* and 60* north and south latitudes in a circulation pattern opposite than the trade winds </li></ul><ul><li>Surface winds move towards the poles in a generally easterly direction </li></ul><ul><li>Remember, the winds are named for the direction from which it blows. </li></ul>
  11. 11. Notice the origin of the wind
  12. 12. Polar easterlies
  13. 13. Wind circulations of Earth
  14. 14. Jet Stream <ul><li>The jet stream is a narrow band of fast moving , high altitude, westerly winds </li></ul><ul><li>Wind , temperature and pressure are all related </li></ul><ul><li>Differences in temperature and pressure cause wind </li></ul><ul><li>The larger temperature gradient in the upper-level atmosphere’s air results in strong westerly winds > this is the cause and effect of the jet stream </li></ul>
  15. 15. Images of the jet stream phenomenon
  16. 16. Fronts <ul><li>A front is a narrow region separating two air masses of different densities </li></ul><ul><li>Remember, density differences are caused by the differences in temperature, pressure, and humidity </li></ul><ul><li>Fronts can stretch over thousands of kilometers across Earth’s surface </li></ul><ul><li>Its when colliding air masses of different densities collide bring dramatic changes in the weather </li></ul>
  17. 17. Cold fronts & Warm fronts <ul><li>Cold fronts displace warm air and forces the warm air up along a steep front </li></ul><ul><li>Clouds showers and sometimes thunderstorms can happen </li></ul><ul><li>Blue line with pointed triangles symbolize a cold front, the blue triangles point in the direction the front is moving </li></ul><ul><li>Warm fronts are where warm air displaces cold air, moves more slowly , encounters less friction with the ground </li></ul><ul><li>Cloudiness and precipitation occur </li></ul><ul><li>Red line with half circles are the symbol for a warm front </li></ul><ul><li>With the circles pointing in the direction the front is moving </li></ul>
  18. 18. Cold Warm
  19. 19. Meteorology symbols for fronts
  20. 20. Stationary front and occluded front <ul><li>Stationary front </li></ul><ul><li>Sometimes two air masses meet and neither one advances into another territory </li></ul><ul><li>The boundary stalls so the air masses stall </li></ul><ul><li>Usually the temperature gradient is so similar and the pressure gradient too </li></ul><ul><li>The symbol is both the triangle and half circle alternated </li></ul>
  21. 21. Rain, rain…go away ! <ul><li>Occluded fronts happen when cold air rushes in and wedges the warm air up </li></ul><ul><li>Warm air is squeezed between the two cold fronts </li></ul><ul><li>Count on rain on both sides of the fronts </li></ul><ul><li>Purple triangles and half circles (semicircles) on a line represent an occluded front on a weather map </li></ul>
  22. 22. High Pressure Low Pressure
  23. 23. Map of the United States of America
  24. 24. Thunderstorms <ul><li>Unequal heating of the Earth’s surface within one air mass can cause a thunderstorm > air-mass thunderstorm </li></ul><ul><li>Another thunderstorm can be formed when cold fronts advance rapidly pushing up a steep cold front boundary </li></ul><ul><li>This rapid movement produces a thunderstorm </li></ul><ul><li>Sometimes a line hundreds of kilometers long and thousands of meters high </li></ul>
  25. 25. Thunderclouds cumulonimbus
  26. 26. New theory for chain reaction of thunderstorms producing lightning
  27. 27. The end